This invention relates to a method and an apparatus for operating a bale opener, particularly as a function of the length boundaries of the bales. The latter may be composed of cotton fiber, chemical fiber or the like. The opener has a carriage arranged for travel along a series of free-standing fiber bales. On the carriage there is mounted a tower which supports a vertically movable cantilever accommodating a rapidly rotating opening device. As the carriage and the tower travel, the opening device passes above the fiber bales for removing fiber from the top thereof. For determining the length boundaries of the bale series, a travelling sensor, upon traversing a bale boundary, transmits an electric signal which is applied to a control device.
In practice, a plurality of fiber bales are arranged in series and in a free-standing manner. When processing different types of fiber, groups of fiber bales may be set up with a space between the groups. The bales within each group contain the same type of fiber material. In order to be able to control the beginning and the end of fiber tuft removal from the bales, the length boundaries, that is, the position of the end faces of the bale series or, as the case may be, the bale groups, has to be determined. According to a known process, markings, such as metal riders are used which are arranged parallel to the fiber bales at the bale boundaries and may be manually shifted and set according to the particular mode of application. The metal riders are sensed by a travelling sensor whose electric signal is applied to the control device of the opener. It has been found in practice that a correct setting of the metal riders is often either overlooked or is not effected in an optimal manner. The consequence of such an oversight is often a drop in the production (since the travelling paths of the carriage are excessively long). Or, longer standstill periods result because an erroneous setting of the machine may cause jamming or an upsetting of the bales.